Expansion Joint Depth

[bbartlet]

I am designing a 3-story, L-shaped, CMU building with hollowcore floors. The building also has a CIP basement. The grade varies along the exterior of the building so that the basement walls are partially exposed (roughly 3' to 4' maximum) in some areas. The building is essentially two 58'-0" wide x 225'-0" long buildings, with an expansion joint at the inside corner of the overall building. The precast spans in the short direction of each building section.
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|_|______|

Typically on a building without a basement, we stop the expansion joint at the slab on grade. So my question is: Can the expansion joint stop just above the first (ground) floor? Do I need to provide the expansion joint through the 1st floor hollowcore but not the CIP foundation walls? Or does the expansion joint need to extend through the basement walls down to the top of footing?

Maybe I'm overthinking this, but any advice is helpful. Thanks.

Brian

 

[JAE]

I would extend the joint through the supporting walls. There will be concrete shrinkage, and possibly thermal, stresses in that re-entrant corner.

 

[dik]

Maybe 8' or 10' or so back from the re-entrant corner (or all corners). An exposed wall 200+ ft in length may require a few joints, depending on the climate.

Dik

 

[hokie66]

I agree with JAE that the movement joint should extend down to the footing, across the reentrant corner as shown in your sketch.

 

[ctb75]

I would run it down to the foundation.The CIP walls will eventually crack, and this way you can backer rod and seal the walls prior to it happening later on its own and decrease the possibility having water intrusion.

 

[bbartlet]

I appreciate everyone's advice. We are leaning towards taking the joint down through the basement walls to the foundations due to the fact that these walls are partially exposed. However, we're still early in design and grading is such that we could probably eliminate exposure, or at the very least get it down to about a foot. If that were the case, would your recommendations stay the same?

 

[hokie66]

Yes.

 

[JAE]

I don't think the dirt level affects whether to bring the EJ down to the footings. If there's no EJ at the corners then you will eventually have an "joint de expansion au naturale".

Don't ask me what language that is.

The joint will magically appear and you will have a torn layer of waterproofing and a leaky wall.